FOUR MONTHS AGO, the American press asked Jimmy Carter to drop out of the presidential race to make room for Teddy Kennedy. At that time, Kennedy led all polls by 40 points. But 14 weeks later, Carter has turned a remarkable political somersault. He defeated Kennedy 59-31 in Iowa, and has a chance of repeating his performance in New Hampshire, although Carter pulled a four-point advantage in Maine.

Carter's gymnastics may not yet be over. The tables turned once, and they could turn again. Unpredictable circumstances gave Jimmy Carter the edge, and they could take it away. The seizure of hostages created a major crisis in Iran, giving him the image of a President under pressure, and diverting attention from domestic issues. The Russian invasion of Afghanistan augmented the impression that Carter faces a more difficult foreign situation than any recent President. The hesitation which formerly hurt his leadership quotient seems to have carried him upward in the popularity polls since these developments.

But the traits that have recently helped Carter--his restraint and caution--could once again turn against him. Carter still has the problems he had as a candidate in 1976. Unlike Kennedy, he has no solid power base he can count on; Kennedy was beating him in the South 2-1 in October. If the hostages should die or events turn against him, Carter could be in trouble.

When the international crisis atmosphere that currently preoccupies the nation dissipates, voters' attention will turn back to domestic issues. Unemployment is once again on the rise and there are signs of recession for this summer. Meanwhile, inflation continues and it is almost certain that before 1981 there will be a new oil crunch with more gas lines and impatience. The press will soon attack Carter for allowing the artificial period of American unity to slip away without the institution of an emergency energy policy. The advantages of being the incumbent could quickly become disadvantages. Kennedy's recent Lazarus speech presented a clear economic policy. It will be heavily debated, but at least his price and wage control suggestion is on the table. If the economy continues to falter, the heat will be on Carter to construct a coherent policy.

Carter has other potential problems. In his Georgetown address, Kennedy finally let his liberal colors fly as he grasped for policies to set him apart from Carter. The speech may not have picked up any new votes but it did awaken a national press corps that clearly looks to the left. (The press has recently focused more on Kennedy's prolems than on his criticisms of the President but this could change as Kennedy puts some ideological distance between himself and the President.)

Kennedy needs the help. His Iowa defeat showed an organization that was not properly prepared. Kennedy has staked his comeback on a victory in the New Hampshire primary. He has a large and hardworking team there, but it might not be enough. In New Hampshire Carter has had an organized group led by J. Chris Brown (the head of Carter's successful '76 effort) working since last summer. He has the support of Governor Hugh Gallen and a majority of the state legislators. He has already pumped Federal grants into the state for highway and railway improvements. In addition, there are hints that the hostages might be returned in time for the New Hampshire race. If Carter can once again turn a primary into a referendum on his Presidency.

By promising victory, Kennedy's comeback team may have made a mistake that could haunt them. Kennedy should have said immediately after Iowa that the first big primary he would point toward would be New York, two months down the road, thereby giving himself breathing room. He should have pointed out that a candidate needs 1700 delegates to take the convention, that there are 37 primaries ahead, and that the winner cannot be predicted by a few early caucuses.

Kennedy's needed victory is still possible. New England voters are fickle and take their candidate's visits very seriously. Kennedy has spent the last weeks in those states, while Carter has sent Vice-president Mondale and wife Rosalyn to the states but has not set foot there himself. If the President can't convince the voters that a crisis continues he might have to start campaigning and debating like the rest of the candidates.

Carter has returned to his position as the man to beat, but he is not invincible. If Kennedy can hang onto his campaign sled in the snows of Maine and New Hampshire, events might turn his way. A two-man Democratic race might be an advantage to the party at this stage. A Kennedy dropout would leave a single target for Republican snipers. But Kennedy has not quit, and his staff remains focussed on the domestic issues that will rise to the fore with a break on the international scene. As they say in politics, it ain't over yet. Hang on to your convention tickets.